-LRB- CNN -RRB- -- On Sunday , ISIS released a new audio recording calling for Muslims to kill Americans and Europeans . In it , an ISIS spokesman states , `` If you can kill a disbelieving American or European , especially the spiteful and filthy French , or an Australian , or a Canadian or any other disbeliever , then rely upon Allah , and kill him in any manner or way however it may be . ''

Last week 's federal indictment against Mufid Elfgeeh provides a reminder of the potential for acts of violence by Americans inspired by al Qaeda 's ideology that the new recording by ISIS seeks to exploit .

Elfgeeh , a 30-year-old American citizen of Yemeni heritage who owns a pizza parlor in Rochester , New York , is accused of attempting to provide support to ISIS and planning to attack American soldiers .

In a new report which we helped co-author , the Bipartisan Policy Center 's Homeland Security Project , a successor to the 9/11 Commission , assessed the current threat posed by such `` homegrown '' militants .

Since 9/11 , jihadist terrorists have killed 25 people in the United States . Each one of those deaths is a tragedy , but none of these attacks were national catastrophes as 9/11 was .

While al Qaeda and its affiliates have failed to conduct any successful attacks in the United States since 9/11 , they have sought to encourage action from militant American citizens , who might be more capable of carrying out terrorist operations in the States than foreign operatives given the stringent security measures now in place .

Unfortunately , this strategy of promoting homegrown extremism has demonstrated some successes , such as Maj. Nidal Hasan 's killing of 13 people at the Fort Hood , Texas , military base in 2009 and the 2013 Boston Marathon bombings , which authorities have said were carried out by Dzhokhar and Tamerlan Tsarnaev .

All of these were inspired by the propaganda of Anwar al-Awlaki , the American cleric killed in a 2011 U.S. drone strike in Yemen after he took up an operational role in al Qaeda in the Arabian Peninsula .

According to the New America Foundation 's research , an astonishing quarter of the 247 jihadist extremists charged since 9/11 either possessed copies of al-Awlaki 's propaganda materials , cited him as an influence or were in communication with him .

The influence of al-Awlaki and al Qaeda in the Arabian Peninsula 's English-language magazine Inspire has persisted even after al-Awlaki 's death .

Worrisomely , around 100 Americans have traveled to fight in Syria with opposition groups , including with ISIS and the al Qaeda-affiliated Nusra Front .

So far , nine Americans have been charged with attempting to support or supporting ISIS or Nusra , according to a count by New America .

In addition , at least two Americans have died fighting with these groups : Moner Mohammad Abu-Salha , who committed a suicide bombing in Syria for Nusra Front , and Douglas McCain , who died fighting with ISIS .

The difficulty al Qaeda and similar groups have had in inspiring Americans to conduct attacks at home is due to the strength of systemic security checks , such as the willingness of Muslim communities to report potential terrorist activity . A third of the extremists charged since 2001 were implicated by tips from family or local community members , according to an analysis by New America .

Of the 51 plots to conduct an attack inside the United States since 9/11 , nearly half were initiated while the suspects were under surveillance by informants , according to a count by New America .

The role that the Muslim community has played as well as aggressive law enforcement efforts using informants have both helped to make the United States a hard target for militants .

Add to these factors other measures taken since 9/11 ; the day that al Qaeda 's hijackers attacked the World Trade Center and the Pentagon , there were only 16 people on the U.S. no-fly list . Today , there are more than 40,000 .

In 2001 , there were 32 Joint Terrorism Task Force `` fusion centers , '' where multiple law enforcement agencies work together to chase down leads and build terrorism cases . Now there are 103 .

Before 9/11 , the U.S. Department of Homeland Security , National Counterterrorism Center , Transportation Security Administration , Northern Command and Cyber Command did n't exist . In 2014 , all of these new institutions make it much harder for terrorists to operate in the United States .

The U.S. intelligence budget also grew dramatically after 9/11 , with Congress giving the government substantial resources with which to improve its counterterrorism capabilities . In 2013 , the United States allocated $ 72 billion to intelligence collection and other covert activities . Before 9/11 , the budget was around a third of that figure : $ 26 billion .

In addition , greater public awareness of the danger posed by terrorism has also made the United States a much harder target . It was his fellow passengers who tackled Umar Farouk Abdulmutallab , the `` underwear bomber , '' on Christmas Day 2009 as he tried to detonate a bomb on Northwest Flight 253 as it flew over Detroit .

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New report seeks to assess threat of terrorist attacks in the U.S.

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Peter Bergen says biggest risk is posed by individuals motivated by jihadist ideology

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Large-scale terror attacks such as 9/11 are less likely due to increased security , he says .